Health capsules

By From Staff and Wire Reports

Sheep and goats

Parents worried that they might not matter much in their offspring's psychological development can take heart from a new study. Researchers say that mothers, at least in the case of sheep and goats, determine social and sexual preferences, especially for males.

Sheep and goats "like ourselves, form close individual attachment bonds with their offspring," researchers write in the current issue of Nature.

Eight male and five female sheep, and four male and four female goats, were given at birth to females from the opposite species to rear. The animals always had social contact with their own species, and some of the foster young's behavior resembled that expected of their own species, such as in the ways they climbed and fed and in the sounds they made. But play and grooming behavior resembled that of their adoptive mothers' species, say researchers from the Babraham Institute in the United Kingdom and the University of Pretoria in South Africa.

In adulthood, the animals were given a choice of animals to mate with. Male sheep reared by goat mothers almost always preferred nanny goats and not ewes. Male goats reared with ewe mothers preferred ewes. The males were not swayed in their choices even after living for three years exclusively with members of their own species.

Female social and sexual preferences, however, could be switched back after one to two years with members of their own kind.

The researchers say their work supports Freud's notion of the Oedipus complex. The apparently more lasting influence of mothers on sons suggests, they say, that males are less adaptable than females to "altered social priorities."

Breakfast benefits

Breakfast makes champions, when it comes to the mood and academic performance of children, a new study suggests.

Researchers from Massachusetts General Hospital offered free breakfasts to children from lower-income families at three public schools. After four months, the scientists evaluated the progress of 133 students through teacher ratings, interviews with parents, academic records and other measures.

In a recent issues of Archives of Pediatric and Adolescent Medicine, the scientists reported that four months of breakfast brought significant improvement in math grades.

Also, the students were less likely to be tardy or absent from school and were less hyperactive. And teachers reported that the children's "psychosocial problems" eased.

Bird smarts

Calling someone a "bird brain" might not be such an insult after all.

A new study suggests that scrub jays can remember important events in their lives: what happened, where it happened and when. Some researchers have proposed that only people were capable of this type of recollection, known as episodic memory.

But in the latest issue of the journal Nature, researchers from the University of California, Davis, and the University of Cambridge in England report that birds do it too. The scientists gave scrub jays some worms and peanuts and the birds hid them in trays.

Later, when the birds were allowed to retrieve their food, they knew they had stored worms and peanuts, knew where to find them, and, even more significantly, the researchers said, remembered when the food had been hidden.

Out of this world

Life would be rough on Phobos, the bigger of Mars' two moons. Astronauts would have to wade through 3 feet of powdery dust left behind by millennia of meteorite impacts. And in the course of just seven hours, visitors would be plunged from a tolerable 25-degree day into a minus-170 degree night, and back again.

Nevertheless, scientists are still interested in this barren world.

NASA recently released new photographs showing huge boulders inside a giant crater that almost splits Phobos in half. This shows that landslides can occur even in gravity only one-thousandth as strong as Earth's, scientists say. The pictures were taken by a camera on the Mars Global Surveyor probe as it circled Mars.

Solar energy

There might be a strange force at work on spacecraft at the fringes of the solar system.

The Pioneer 10 and 11 probes might be subject to a slight acceleration directed toward the sun, a new study says. Scientists have tried to account for the force with ordinary explanations, such as gravity, and have failed so far. They suggest instead that an as-yet-unexplained aspect of physics may be to blame.

Pioneer 10 was launched in 1972, Pioneer 11 the next year, and the unmanned probes have traveled away from Earth in opposite directions ever since. Scientists have been monitoring radio signals from the spacecraft to keep track of their position and speed.

In 1980, researchers first noticed an accelerative force acting on the Pioneer probes, directed toward the sun. The force couldn't be accounted for by the gravitational tug of other objects, gas leaks from the spacecraft, or any other mundane explanation. Now, scientists have nearly two more decades' worth of data showing the unexplained acceleration, including the same effect on the Ulysses spacecraft, which studied the sun.

John Anderson, of the Jet Propulsion Laboratory in Pasadena, Calif., and colleagues describe the work in a paper scheduled to be published next month in the journal Physical Review Letters.

Feel the noise

Your sense of touch might work better with a little noise thrown in.

Experiments show that a little bit of electrical "noise," or an electrical signal applied to the fingertips, can help people detect touch.

The research is meant to help older people who might have lost much of their touch sensitivity. But on a more basic level, scientists say, the work is some of the first evidence in humans for the phenomenon known as stochastic resonance.

Stochastic resonance is basically good noise, when the presence of noise actually helps in the detection of a signal.

Boston University researcher Kristen Richardson and colleagues studied 11 young people to see whether stochastic resonance occurs during human touch. Without a subject knowing it, the scientists used a device to press lightly on the fingertips, just below the level that should have been detectable. Half the time, the researchers also added a low-level electrical current flowing through the subject's fingers.

Nine subjects picked up on the fingertip pressure when the electrical current also was flowing through them, the scientists report in the journal Chaos. The researchers suspect that the electrical stimulus may help nerve cells in the fingers fire off messages of "being pressed" to the brain.